Propagation dynamics of meteorological, agricultural, and vegetation droughts in China

Abstract

Meteorological drought (MetD) serves as the primary driver of other drought types by altering the hydrological cycle and initiating subsequent droughts. However, the mechanisms of propagation from MetD to agricultural drought (AgrD) and vegetation drought (VegD) remain poorly quantified across China’s diverse climatic gradients. Elucidating this complete propagation pathway is critical for enhancing drought monitoring and early warning systems across various ecosystems. This study employed the Standardized Precipitation Index (SPI), Standardized Soil Moisture Index (SSMI), and Vegetation Condition Index (VCI) to quantify MetD, AgrD, and VegD, respectively. The results revealed significant disparities in both the average duration and frequency of MetD, AgrD, and VegD across China. MetD exhibited the highest mean frequency (1.43 times/year), exceeding AgrD (0.54 times/year) and VegD (1.17 times/year). All drought types demonstrated alleviation trends, as evidenced by significant increases in SPI (57.11 %), SSMI (86.63 %), and VCI (65.00 %). MetD exerted the strongest influence on AgrD, while AgrD had a more substantial effect on VegD than MetD. The average propagation time from MetD to AgrD was 7.38 months, significantly shorter than from MetD to VegD (12.94 months) and from AgrD to VegD (12.79 months). Propagation processes were shorter in summer and autumn compared to spring and winter, influenced by climate and vegetation types. These findings provide a scientific foundation for drought risk assessment, ecological restoration, and vegetation recovery initiatives in China, contributing to the development of a more comprehensive drought monitoring system.